All Questions
Tagged with electromagnetic-radiation laser
118
questions
11
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4
answers
2k
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Can the laser light, in principle, take any wavelength in the EM spectrum?
Can the laser light, in principle, take any wavelength in the EM spectrum? I don't think there is what prevent this in principle, right?
- 959
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0
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43
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Spherical laser beam terminology
I am currently seeking the correct terminology for a beam that expands linearly from a fixed point, resulting in its wavefronts forming spherical surfaces. However, the beam does not expand in all ...
- 153
0
votes
2
answers
131
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Determining Gaussian beam parameters of a laser
The intended output of many lasers in laser scanning is Gaussian. At distance $z$ from the waist, the radius of a Gaussian beam is calculated as
$$w(z) = w_0 \sqrt{1+(z/z_R)^2},$$
where $w_0$ is the ...
- 153
1
vote
1
answer
179
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Is a neutron deflected sideways by a laser beam?
Is a freely moving neutron deflected sideways when a laser beam is directed at it from the side? It would be great if the question could be considered from the two points of view that the laser beam ...
- 10.6k
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0
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54
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The Stark-Lo Surdo effect
What does the Stark-Lo Surdo effect consist of in the interaction of the electromagnetic field and the active medium in a laser? I thank those who want to give a clear and concise answer.
In my ...
- 121
2
votes
1
answer
682
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Why can't we use polychromatic light for making laser?
As far as I have read in my textbooks, we can only use monochromatic light for making a laser. Why can't we use polychromatic one? What if we try to make a laser out of a polychromatic light?
156
votes
1
answer
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What is an "attosecond pulse", and what can you use it for?
The 2023 Nobel Prize in Physics was announced today, and it was awarded to Pierre Agostini, Ferenc Krausz and Anne L’Huillier, for
“experimental methods that generate attosecond pulses of light for ...
- 134k
0
votes
1
answer
79
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How can a laser be narrow?
In my understanding, light works as follows: every point in space where there is light, this light works as a point source. When we progress in time, the light spreads out from there in all directions ...
- 1,440
12
votes
2
answers
2k
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On the (non)linearity of electromagnetism
As a student you are typically told that Maxwell's equations (ME) in vacuum are linear. However, it seems that for extremely high electromagnetic fields the equations for electromagnetism turn out to ...
- 1,211
2
votes
3
answers
266
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Coherent unpolarized laser light
I notice that in semiclassical treatments of laser light absorption by particles, they treat the laser beam as a coherent oscillating electric field over the form $E_0\cos(kx-\omega t)$, sometimes ...
- 366
2
votes
1
answer
439
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Laser induced explosion (detonation)
I have a question involving quite the wacky (and silly) hypothetical. It's a part of an ongoing argument I'd like to settle. Of course, I have no background in physics which is why I came here, so I ...
- 21
1
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0
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57
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Decoherence of a laser beam via oil emulsion
This is sort of a followup to an earlier question that I posted regarding how to destroy the temporal and/or spatial coherence of a laser beam. It was suggested to me that I could use a rapidly ...
- 366
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1
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101
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Is there laser operating at megahertz?
I have tried to find a laser with working frequency at megahertz by Google but failed. Is there exist one?
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3
votes
1
answer
1k
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Is laser light a standing wave?
If I understand it correctly the light waves are standing within the laser cavity as they bounce off the walls. Does that mean they remain standing as they leave the cavity? There is nothing out there ...
- 1,297
2
votes
2
answers
125
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Is stimulated emission emitted by a rotating classical dipole subject to a resonant oscillating wave beamed?
Consider a dipole, $\pm q$ connected by a rigid rod of length $2L$, spinning around its center in the $x-y$ plane with angular frequency $\omega$, such that the charges follow $\vec{r}_{\pm q}(t) = \...
- 572
1
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4
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87
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Seeing trajectory of light
I had gone through a few posts on this topic in this community,however the doubt i have is different from them a bit. There it was said that we do not actually see a laser beam unless they are ...
- 1,179
1
vote
1
answer
75
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Can fusional nuclear compression theoretically be achieved with a unidirectional compressive force?
In other words, is it theoretically possible to get an energy-profittable nuclear fusion reaction by simply slamming compressive force into some nuclei from a single laser compressing from one ...
- 29
1
vote
1
answer
175
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Why are pulsed lasers are the main tool used in nonlinear optics applications, instead of CW sources?
Why we often use pulsed lasers for nonlinear optics applications (such as SHG) instead of continuous wave lasers?
- 367
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1
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30
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How to relate laser pulse characteristics to the degrees of ionization of a target (i.e. how many electrons get removed per atom)?
Say I have a lithium foil as a target for a laser. Li has $3$ protons and $3$ electrons and therefore $3$ degrees of ionization associated with $3$ ionization energies (for removing the first, second ...
- 255
11
votes
1
answer
2k
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Can a Black Hole be moved by lasers?
I've read that an object colliding with a black hole will move it, as it would any other object. Could a laser continuously fired into a black hole move it?
- 719
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vote
0
answers
34
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Why laser pulses are often assumed to have a hyperbolic secant shape [duplicate]
For mathematical simplicity we often assume that the laser pulses have a Gaussian envelope. But many theoretical models still predict hyperbolic secant pulse shapes for the laser. Any particular ...
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0
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37
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Role of quantum fluctuation of light in lasers: simple explanation [closed]
Firstly, I am not an expert and have no background in quantum physics and in physics. I am studying laser technology and have found out that the quantum fluctuation of light will be a limitation of ...
- 11
1
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1
answer
191
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Is it possible to “encrypt” laser beams such that they would need to be “decrypted” to be seen?
I was playing a video game that had some guns equipped with laser sights. It had me think if it would be possible to transmit the laser beam in such a way that it is only visible to an observer ...
- 121
1
vote
1
answer
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Idea to Modulate a Laser with a 1/4 Wave Plate
Procedure:
Take a linear polarized red laser beam and send it through a 1/4 wave plate to create elliptically polarized light. Then send this elliptical polarized light through a linear polarized ...
- 4,711
2
votes
1
answer
54
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Devices for the generation of polarized light
In many papers dealing with the generation of polarized states of light in imaging applications, Photo Elastic Modulators (PEM) is one of the most chosen devices to modulate the polarization of the ...
- 61
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2
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578
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Is it possible to create a laser in the extremely low frequency radio spectrum?
I have been reading about effort to push lasers into the hard X-Ray and soft Gamma Ray range, been quoted as one of the most important problems in physics according to Vitaly Ginzburg.
However, would ...
- 477
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votes
1
answer
125
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How theoretician or experimentalist knows, exactly what is happening in the Laser (He-Ne) gas tube?
Principle of (He-Ne) Laser : Here Helium atoms don’t produce direct laser photons, but instead, the Helium atom is excited by an electric field. Then Helium atoms will collide with Neon atoms while ...
1
vote
2
answers
143
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Why does increasing radiation frequency produce narrower collimated beams?
In the context of a THz Gaussian beam $(1)$, it is stated:
Terahertz output radiation at higher frequency produced a narrower collimated beam owing
to diffraction effects (...)
What kind of ...
- 753
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vote
2
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106
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Why do artificial transmissions of coherent EM waves tend to be isotropic at radio frequencies but directional at visible frequencies?
This is a somewhat soft question, and I'm far from an expert on the subject, so it's possible that my premise is factually incorrect.
The practical generation mechanisms for useful real-world coherent ...
- 48.4k
0
votes
0
answers
191
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Modeling Gaussian Beam Focusing
I am trying to model beam focusing using machine learning algorithms in Python with the goal of building a model that learns to focus the beam to the smallest point possible. However, I am lost as to ...
- 131
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1
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33
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Are 'Terahertz-pulse lasers', like, 'Terahertz time-domain spectroscopy' and such, of Terahertz-frequency or trillion-pulses-per-second?
From Phys.org:
Light-controlled Higgs modes found in superconductors; potential sensor, computing uses.
The mode can be accessed and controlled by laser light flashing on the superconductor at ...
- 4,509
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1
answer
75
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Are Field Beams Possible?
I was recently wondering why the field force between two objects is proportional to the square root of the distance (sometime you just take things for granted). This comes from the inverse-square law, ...
- 1
1
vote
2
answers
43
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Area of detectable optical transmission as a function of distance in the context of SETI
The relevant page on SETI's official website states:
The SETI Institute, along with scientists from the University of California's Lick Observatory, UC Santa Cruz, and UC Berkeley has coupled the ...
- 545
0
votes
1
answer
372
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Why does a shorter-wavelength laser beam diverge less than a longer-wavelength one?
Also, does this phenomenon apply only to lasers, or also to other EM beams?
I wonder if the answer is related to the fact that diffraction limit(s) are proportional to wavelengths...
- 4,509
-2
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1
answer
190
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How to hide radio communications between airplanes? [closed]
I have 2 airplanes and I would like completely hide the communications between them.
There is a possible way that this communications would not be detected by our radio receivers around the world? ...
- 9
2
votes
1
answer
275
views
Fresnel-Kirchoff integral and Huygens principle
Consider a monochromatic, uniformly polarized, EM wave:
$$E(x,y,z,t)=\tilde E(x,y,z)e^{iwt}$$
If on a certain plane $z=z_1$ the field $\tilde E(x_1,y_1,z_1)$ is known, we can find $\tilde E(x,y,z)$ on ...
- 1,904
2
votes
1
answer
218
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Laser flux power density and Raman scattered radiation
I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter Larkin. In a section entitled The Raman Scattering Process, the author says the following:
The intensity of ...
- 889
1
vote
0
answers
72
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Speckles max intensity paradox
Wikipedia says (link) that in the limit of many interfering waves the distribution of intensities (which go as the square of the vector's length) becomes exponential
$${\textstyle P(I)={\frac {1}{\...
- 11
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0
answers
49
views
How to explain light beams in terms of wave theory?
How can we explain the formation of light beams in terms of wave theory?
According to wave theory, shouldn't the source point of beams emit radiation omnidirectionally, rather than a concentrated ...
- 533
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votes
2
answers
42
views
Can an electromagnetic wave be pulsated at the same frequency of the wave itself?
This is a thought experiment that's been bugging me for some time and I haven't been able to find any literature on this topic. I am not a physicist, please bear with me :).
Suppose I have a 500nm ...
- 25
1
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0
answers
16
views
Does a laser's listed wattage or joules include the frequency? Or just the amplitude?
In other words, if the number of photons in two different lasers is the same, but the second laser has a higher wavelength, does the second one have more 'wattage' or more total joules?
(Since higher-...
- 4,509
0
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0
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169
views
Infinite universe and the impossibility of monochromatic light and infinite plane waves
I recently asked a question relating to this excerpt from the textbook Optics, fifth edition, by Hecht:
Mathematically, the plane wave extends out to infinity in all its directions, and, of course, ...
- 889
4
votes
2
answers
456
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Non-monochromatic (multi-wavelength?) lasers
I was recently doing some reading on lasers, and I came across the fact that truly monochromatic light is impossible, which then obviously implies that truly monochromatic lasers are impossible. But ...
- 43
-1
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1
answer
42
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Laser emission frequencies: does that physically represent the frequencies if it was turned on for infinite time?
Consider you have a laser that has a given emission spectrum.
Does this emission spectrum physically represents the electromagnetic field it would emit if it was turned on for an infinite amount of ...
- 1,450
2
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0
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34
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Will a magnet diffuse/defocus a laser?
I have read through hundreds of questions here and we discuss why light is not bent by an electric or magnetic field (at least not at easily visible levels in the classical sense), but that there is ...
- 121
3
votes
1
answer
605
views
Would a radio frequency (RF) laser have any advantage over ordinary radios?
In the radio part of the electromagnetic spectrum it is really easy to make very clean and powerful RF waves using modern electronics, and it really isn't that hard to make arbitrary RF waves.
But ...
- 7,931
4
votes
4
answers
2k
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Does putting an aperture in a laser beam make the smallest point it can be focused to larger or smaller?
If you put an aperture in a laser beam to block some of it, I would imagine that the spot it can be focused to becomes larger due to diffraction. The numerical aperture of the system is limited by ...
- 43
1
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1
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455
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Confused about intensity of a laser beam
For normal natural light coming from the sun, the electromagnetic waves emanate from the sun with a spherical wavefront, then we can calculate the intensity of these waves reaching us on Earth by $ I =...
- 753
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0
answers
46
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Do red lasers shoot longer than green ones?
I am aware of the fact that our eyes are most sensible to green color and therefore green lasers seem stronger than other colors when being scattered through the air. However, since red wavelength are ...
- 191
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vote
2
answers
184
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Why do thermal currents affect light but wind does not?
I notice if I put heat under a laser beam it will cause the beam to shimmer. The heated air is causing a disturbance in the air which affects the light. Yet, I can blast a stream of air from a ...
- 4,711